Sixty-nine years ago today, the United States dropped an atomic bomb on the city of Hiroshima. Three days later, on Aug. 9, 1945, the U.S. dropped a plutonium bomb on the city of Nagasaki.

An estimated quarter of a million people died as a result, but only about half on the first day. The rest suffered inhumanely for days and months afterward from severe burns and radiation sickness before dying. Almost all of Hiroshima’s health care providers were killed.

We hesitate to even imagine the horror experienced by people on those days.

Scientists still debate whether the exposure to radiation caused birth defects in the children of survivors, but the elevated cancer deaths among the bomb survivors is well documented.

The hibakusha, the Japanese term for bomb survivors, have endured the additional pain of discrimination within their own country by people who don’t understand the effects of radiation sickness. Some people still think it is contagious.

On the anniversary of the world’s only nuclear attack, the mayor of Hiroshima makes a speech urging the world to abandon the false security of the global nuclear arms race. It’s a plea everyone in the world should take seriously.

When conflicts break out around the world, as they have today in Ukraine and the Middle East, there is always the danger that one side or the other might deploy a nuclear weapon.

During the peak of the Cold War era, both Russia and the U.S. operated on the nuclear deterrence theory. It was an understandable, but mistaken, belief that no nation would attack another nation that had an arsenal of nuclear weapons.

The unfortunate nuclear arms race began because of that line of thinking. Even though several good-faith attempts have been made toward disarmament since, there are more than 17,000 nuclear weapons scattered all over the world today.

Put into the wrong hands – North Korea, for example, or any number of fringe terrorist organizations – we can only imagine the devastation those weapons could cause.

Knowing those weapons are out there and that many nations have stockpiled plutonium from spent nuclear fuel, which can be converted into nuclear bombs, should make every inhabitant of this planet uneasy.

It’s alarming when North Korea conducts nuclear tests, or when we learn that China is building up its nuclear war chest and Iran is developing nuclear capability.

Japan faces the danger of instability in Northeast Asia, where unpredictable triggers could set off China or North Korea.

In last year’s Hiroshima Peace Declaration, the city’s mayor asked world leaders, “Do you honestly believe you can continue to maintain national security by rattling your sabers?”

Or, as President Obama said in speech in Berlin, “We may no longer live in fear of global annihilation, but so long as nuclear weapons exist, we are not truly safe.”

And yet, despite Japan’s leadership and the promising statements of presidents and other world leaders, nuclear disarmament has never been achieved. On the contrary, from a global perspective, the dangers have actually increased.